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Scientists have decoded the genome of parvovirus B19 is one of the oldest known viral genomes.
Researchers from Russia, Kyrgyzstan, Canada and several European countries have read the genomes of human parvovirus B19 by the age 500-6900 years. The data obtained showed that this virus that causes infectious erythema in children and joint pain in adults, affects people for over 12 000 years, not a century and a half, as previously thought. Scientific article published in Proceedings of the National Academy of Sciences (PNAS).
The majority decrypted at the moment of viral genomes does not exceed 50 years. DNA and RNA viruses from an older biological materials are getting rare, as these molecules because of their small size remain worse than the DNA and RNA of humans and other animals. But this does not mean that all viruses infecting at present, people have learned to do it recently. Therefore, the authors of the new work has questioned the fact that the mass of the subtype parvovirus B19, most often striking children, began to infect our species only in the 1960-ies, and the common ancestor of all existing B19 appeared only in the early nineteenth century. Namely, the evaluation gave the researchers the results of the analysis of the genomes of parvoviruses B19 by the age of 70 years or less.
The authors of the new article received 10 fragments of the genomes of parvoviruses B19 from bone and teeth of human remains found in Kyrgyzstan, Russia, Poland, Greenland, Sweden, the Czech Republic and the UK. The age of the finds ranged from 544 to 6862 years. The most complete (99.7 percent DNA preserved) the genome of parvovirus were presented with a sample from Kyrgyzstan aged 1518 years, the least complete (63.9% DNA preserved) — finds from the shores of lake Baikal (the tract shaman) aged 41 to 46 years. The scientists compared the obtained nucleotide sequence of DNA of parvovirus B19. So they can evaluate what kind of mutation in the genome of this virus appeared earlier, some later, and approximately when it began to infect Homo sapiens.
According to researchers, the last common ancestor of all ten found variants of parvovirus B19, there were about 12.6 thousand years ago. Now there are three subtypes of parvovirus B19, of which the most common cause of illness in people is caused by a virus of the first subtype. Analysis of the genomes of ancient parvoviruses showed that, similar to the present, he appeared more than 6.8 thousand years ago, not in the 1960s, as shown by the results of earlier studies. This estimate of the age of parvovirus B19 in the first subtype given on the basis of speed of mutations occurring in its DNA. Given the small percentage of difference between the genomes of viruses age 500-6900 years, this rate is much lower than other researchers believed the parvoviruses.
Parvovirus B19 is a common, although not life-threatening pathogen. It affects primarily the red blood cells, including in bone marrow, and is particularly common among blood donors. Its presence in the body can outwardly not be shown, however, in children it often causes infectious erythema — red rashes all over the body. In adults it causes arthralgia — periodic pain in the joints without inflammation. From the point of view of medicine to study the origin of the parvovirus B19, of course, important, but much more interesting is another aspect of the described operation. This new study shows that samples of nucleic acid of viruses can be extracted from human remains age up to several thousand years.